1. Field of the Invention
The present invention relates to a liquid jet apparatus such as, e.g., an ink jet recording apparatus and, more particularly, to means for detecting the substantial presence and absence of the liquid stored in the liquid storing means.
2. Description of the Prior Art
Liquid jet recording apparatuses such as an ink jet recording apparatus and the like are getting most of the attention as new recording means since they have advantages such that direct recording is possible, coloration is easy and noise is reduced. Particularly, on-demand type ink jet recording apparatus is becoming a principal full color printer technology since it is cheap and can be miniaturized.
However, conventionally, this kind of recording apparatus has the drawback that the emission of ink becomes unstable due to an increase in viscosity of ink since the volatile substance in the ink at the point of the recording head (ink jet head) may evaporate. Further, since it is necessary to form the ink tank, or recording liquid storing means, of flexible material, it is difficult to detect whether or not ink remains in the tank. Therefore, there is another drawback namely misrecording due to lack of ink. In the former case, it has been tried to remove the ink having increased viscosity from the orifice opening at the point of the head by an apparatus for preventing choking, so that a certain extent of effect is obtained. However, when the choking preventing apparatus and apparatus for detecting the amount of remaining ink in the tank are individually provided, the equipment becomes complicated, causing the size and cost of the apparatus to increase. In particular, an increase in the number of kinds of inks used for coloration or the like exacerbates this tendency. On the other hand, when the point of the head is capped for prevention of drying of the head, the ink meniscus at the point of the head retracts, thereby causing a drawback such that the recording (printing) becomes unstable.